CAPE Chemistry Exercise #1
To test the accuracy of measurements. 2014 Mark December
Name: ..
Background
An uncertainty is a natural variation in a measurement that
comes about for a variety of reasons including, the premise that no
instrument is exactly accurate,
different people may be using different types of instruments and
the instruments adjustment may have changed.
Activity 1: Calculating the volume of a coin along with the
absolute uncertainty of the measurement using a millimetre
rule.
Thickness of the coin, h: h = 0.15 cm
absolute uncertainty
relative uncertainty
3 marks
Diameter of coin, d: d = 2.2 cm
absolute uncertainty
relative uncertainty
3 marks
== volume of coin, V1 = d2 h 4 V1 =
relative uncertainty
3 marks
Activity 2: The coin was weighed on an electronic balance and
the mass was recorded.
Mass of the coin, m: m = 4.12 g
absolute uncertainty
relative uncertainty
3 marks
== density of the coin, 1 = m V1
3 marks
The volume V2 of the coin was measured by placing it into water
in a measuring cylinder and recording the volume of water
displaced. After that 17 coins were
collected and placed all together in one measuring cylinder with
water. It was found that the total volume V3 of all 17 coins was
9.0 mL.
NB: The smallest graduation on a measuring cylinder is
0.1mL.
Final Volume = 59.01 mL Initial Volume = 59.00 mL V2 =
absolute uncertainty
relative uncertainty
3 marks
Volume of 17 coins = 9.0 mL == V3 = the volume of a number of
coins The number of coins
absolute uncertainty
relative uncertainty
3 marks
Calculating the densities using V2 and V3 in the spaces
below.
2 = m = V2
relative uncertainty
3 marks
3 = m = V3
relative uncertainty
3 marks
Question 1: State which of the above method used to determine
density is most accurate and provide a justification for your
choice.
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2 marks
Suggest an improvement.
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1 mark
